Welsh Rebellion

The Welsh Rebellion occurred during the 880s when the Welsh principalities of Gliwissig and Gwent rebelled against their Anglo-Saxon overlord, King Alfred the Great of Wessex. Gliwissig was the first to rise against King Alfred, while Gwent followed shortly after the arrival of Aelfwald's Saxon army. Ultimately, the Welsh rebels failed to coordinate an effective response to the invasion, and they were both forcefully conquered and deprived of their autonomy.

Background
The Brythonic kingdoms of Wales had been rivals with the Anglo-Saxon heptarchy for centuries, starting with the Saxon invasions of the British Isles during the late 5th century. By the start of the 9th century AD, the Britons were confined to the corners of Britannia, namely Alt Clud in Scotland, Wales, and Cornwall. The start of the Viking invasions of England in 867 presented the Britons with an opportunity to throw off the Saxon yoke, and, in 879, Mercia's invasion of Wales caused Gwynedd to co-opt the nearby factions and unite them against the Saxon threat in the east. The Mercians - who were forced to battle the Vikings of Djurby to the east and Northymbre to the north, as well as the Welsh - were unable to deal with the pressure, allowing for Welsh and Danish armies to conquer large parts of the kingdom.

Mercia was not the only Saxon kingdom with a stake in Welsh affairs, however. Wessex, ruled by King Alfred the Great, was the overlord of the southern Welsh kingdoms of Gliwissig and Gwent, both of which paid tribute to King Alfred in exchange for a great deal of autonomy. However, Gwynedd's successes against the Mercians and the rising power of Wessex persuaded King Owin of Gliwissig to declare independence from Wessex and break free of Saxon rule. Gwent initially stayed loyal to King Alfred, and its allegiance to Wessex forestalled any attempt by Gliwissig to attack Wessex's possessions.

King Alfred sought to crush the Welsh rebellion after Gliwissig's emissaries refused to consider peace or returning to the fold, and he dispatched his general Aelfwald from Southampton with a sizeable army. Aelfwald brought his army across South West England before sailing across the River Severn and making landfall to the west of Gwent's capital of Cair Gwent (Caerwent, Monmouthshire).